Cavity-back iron type club heads, also known as perimeter weighted irons, are known to have a concentration of mass about the periphery of a rear surface of the club head. This concentration of mass is in a raised, rib-like, perimeter weighting element that substantially surrounds a rear cavity, which comprises a major portion of the rear surface of the club head. In addition to locating a substantial amount of mass away from the center of the club head behind the club face, the rib-like perimeter weighting element acts as a structural stiffener, which compensates for reduction in face thickness in the cavity region.
Cavity-back clubs are quite forgiving when a ball is struck away from the optimal impact point, or sweet spot, of the club face, in part due to increased moment of inertia provided by the perimeter weighting element. On such off-center hits, distance lost due to head rotation, resulting from the ball striking force being applied distal from the sweet spot, is minimized. Further, harsh vibrations transmitted through the shaft to the hands of the golfer are also minimized.
Therefore, cavity-back clubs permit a golfer to strike the ball anywhere within a significant area on the clubface without realizing significant negative physical effects or performance losses. For this reason cavity-back clubs are well suited to inexperienced or less skilled golfers, who struggle to consistently and accurately strike a golf ball at the sweet spot of the club head. Skilled golfers, who consistently strike a golf ball at the sweet spot of their club heads have found that cavity-back clubs generally provide less feel because they are designed for maximum forgiveness. To these golfers, cavity-back clubs may not provide the feedback or ball control required for shaping their shots (commonly referred to as “working” the ball) to accommodate a variety of playing conditions.
Muscle-back or blade irons are characterized by a thick lower portion known as the “muscle”, which extends along the entire length of the head. A thin upper portion extends upwardly from the muscle and behind the face of the club, and is commonly referred to as the blade portion. The blade portion has no reinforcement ribs or perimeter weighting, the only concentration of mass being in the muscle of the club, behind its sweet spot. Typically, a muscle-back club head is smaller than a cavity-back head, due to the solid muscle portion having substantial mass. This configuration provides excellent feel when a ball is struck at the sweet spot, but typically yields a harsher sensation as well as greater distance loss associated with off-center shots in comparison to similar shots hit with cavity-back irons. For these reasons, muscle-back clubs are generally better suited to skilled golfers who consistently strike the ball within close proximity of the sweet spot. Muscle-back clubs therefore are more difficult to hit, but provide skilled golfers with desired control and shot shaping ability, or workability.
The benefits of cavity-back irons are best realized in the lower numbered irons, or long irons, which are known to be the most challenging to hit effectively for many golfers of all skill levels. By comparison, higher numbered short irons, even those of the muscle-back type, are generally perceived as being substantially easier to hit effectively. For this reason, golfers of all skill levels generally forfeit the forgiveness benefits of cavity-back clubs when they select the shorter irons in a set, for example wedges with typical lofts from about 44 to about 66 degrees, in exchange for the workability and feel of muscle-back clubs.
Although it is generally easier effectively to strike a short, muscle-back iron than a long, muscle-back iron, a need nonetheless exists for improvements in the feel and forgiveness of muscle-back irons.